Kinetic control of interpenetration in Fe-biphenyl-4,4′-dicarboxylate metal-organic frameworks by coordination and oxidation modulation

Bara, D. J. , Wilson, C. , Mörtel, M., Khusniyarov, M. M., Ling, S., Slater, B., Sproules, S. and Forgan, R. S. (2019) Kinetic control of interpenetration in Fe-biphenyl-4,4′-dicarboxylate metal-organic frameworks by coordination and oxidation modulation. Journal of the American Chemical Society, 141(20), pp. 8346-8357. (doi: 10.1021/jacs.9b03269) (PMID:31017428)

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Phase control in the self-assembly of metal-organic frameworks (MOFs) is often a case of trial and error; judicious control over a number of synthetic variables is required to select the desired topology and control features such as interpenetration and defectivity. Herein, we present a comprehensive investigation of self-assembly in the Fe-biphenyl-4,4′-dicarboxylate system, demonstrating that coordination modulation can reliably tune between the kinetic product, non-interpenetrated MIL-88D(Fe), and the thermodynamic product, two-fold interpenetrated MIL-126(Fe). Density functional theory simulations reveal that correlated disorder of the terminal anions on the metal clusters results in hydrogen-bonding between adjacent nets in the interpenetrated phase and is the thermodynamic driving force for its formation. Coordination modulation slows self-assembly and therefore selects the thermodynamic product MIL-126(Fe), while offering fine control over defectivity, inducing mesoporosity, but electron microscopy shows MIL-88D(Fe) persists in many samples despite not being evident by diffraction. Interpenetration control is also demonstrated using the 2,2′-bipyridine-5,5′-dicarboxylate linker; it is energetically prohibitive for it to adopt the twisted conformation required to form the interpenetrated phase, although multiple alternative phases are identified due to additional coordination of Fe cations to its N-donors. Finally, we introduce oxidation modulation – the use of metal precursors in different oxidation states to that found in the final MOF – to kinetically control self-assembly. Combining coordination and oxidation modulation allows the synthesis of pristine MIL-126(Fe) with BET surface areas close to the predicted maximum for the first time, suggesting that combining the two may be a powerful methodology for the controlled self-assembly of high-valent MOFs.

Item Type:Articles
Additional Information:This project received funding in part from the European Research Council (ERC) under the European Union’s Horizon 2020 Programme for Research and Innovation (grant agreement no. 677289, SCoTMOF, ERC-2015-STG). Via our membership of the UK's HEC Materials Chemistry Consortium, which is funded by EPSRC (EP/L000202, EP/R029431), this work used the 'ARCHER UK National Supercomputing Service ( MMK is grateful to the Deutsche Forschungsgemeinschaft (DFG Research Grant KH 279/3) and Emerging Talents Initiative (ETI) program of the FAU Erlangen-Nürnberg for financial support.
Glasgow Author(s) Enlighten ID:Wilson, Dr Claire and Sproules, Dr Stephen and Forgan, Professor Ross and Bara, Mr Dominic
Authors: Bara, D. J., Wilson, C., Mörtel, M., Khusniyarov, M. M., Ling, S., Slater, B., Sproules, S., and Forgan, R. S.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Journal of the American Chemical Society
Publisher:American Chemical Society
ISSN (Online):1520-5126
Published Online:24 April 2019
Copyright Holders:Copyright © 2019 The American Chemical Society
First Published:First published in Journal of the American Chemical Society 2019 141(20):8346-8357
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
689571SCoTMOFRoss ForganEuropean Research Council (ERC)677289SCHOOL OF CHEMISTRY